1. Field of the Invention
This invention relates to polyvinylchloride homopolymer and copolymer foam compositions prepared by frothing. These compositions contain silicone surfactant frothing agents and oleophilic frothing aids.
2. Description of the Prior Art
Techniques for the preparation of polyvinylchloride homopolymer and copolymer foam compositions from plastisols are well known in the polymer art. Also, the literature on polyvinylchloride and acetate modified polyvinylchloride resin plastisol preparation is quite extensive. Reference may be made to the following publications:
Boehm and Dietz, "Vinyl Froth Foams Via the Oakes Continuous Mixer", Diamond Shamrock Chemical Company Technical Service Information Report No. 3-71, Apr. 30, 1971. PA1 Boehm and Dietz, "The `Ulok` PVC Carpet Backing System", Diamond Shamrock Chemical Company Technical Service Information Report No. 4-71, May 5, 1971. PA1 Simoneau, "Silicone Surfactants in Mechanically Frothed Vinyl Plastisol Foams", Rubber World, p. 49, August 1970. PA1 Renshaw and Garlick, "How to Back Carpets with PVC", SPE Journal, Vol. 28, p. 21 (1972). PA1 Keil and Webb, "Mechanically Frothed Vinyl Plastisol Foams", Journal of Cellular Plastics, Vol. 6, No. 4, p. 3, July/August, 1970. PA1 1. a foamable plastisol which is a mixture of PA1 2. from about 1 to about 5 phr of one or a mixture of silicone frothing agents, and PA1 3. from about 5 to about 10 phr of one or a mixture of frothing aids which is a phosphate ester, phosphite ester, borate ester, organic nitrogen compound or organic nitrogen-sulfur compound. PA1 4 - 40% vinylidene chloride PA1 5 - 20% acrylic ester such as methyl acrylate, octyl acrylate PA1 5 - 40% vinyl ethers such as n-butyl vinyl ether, cetyl vinyl ether PA1 5 - 20% maleic and fumaric esters such as diethyl maleate, di-2-ethylhexyl fumarate PA1 5 - 40% acrylonitrile PA1 3 - 8% ethylene PA1 3 - 15% propylene PA1 1. PVC homopolymer dispersion grade resins PA1 2. PVC-PVA copolymer dispersion grade resins PA1 3. PVC homopolymer extender grade resins PA1 4. PVC-PVA copolymer extender grade resins. PA1 1. Phthalate plasticizers PA1 2. Phosphate plasticizers PA1 3. Low temperature plasticizers PA1 4. High molecular weight plasticizers PA1 5. Miscellaneous plasticizers
Polyvinylchloride (PVC) foam for use as carpet and rug backing and in other markets has certain inherent advantages over other foamed polymers. PVC foams for rug and carpet backing have high tensile and tear strengths; they are more resistant to scuffing, and they have stronger tuff-lock. Also, of significant importance, PVC foams are more fire retardant than other foam polymers.
There are three general methods for producing foam from plastisols . . . compressed gas, chemical blowing agents, and frothing (mechanical whipping). In the frothing method, the most widely used method for producing fine open cell foam, PVC foam is produced by mechanical whipping of the plastisol to incorporate air into the plastisol and then fusing the foam at a relatively low temperature of about 270.degree. to about 290.degree.F. About the only disadvantage of this relatively simple frothing method is the high cost of the silicone surfactant frothing agent.
Additional information on the preparation of PVC foam compositions by frothing can be found in U.S. Pat. No. 3,511,788 -- Keil -- issued May 12, 1970. This patent describes the preparation of froths using silicone surfactant frothing agents and the use of these foams in various applications including the coating of substrates such as rugs and carpets.